[PATCH] Fix ICE in nonnull warning on OFFSET_TYPEs (PR c++/68653)

[Marek Polacek]

We were hitting the assert in nonnull_arg_p that only wants to see POINTER_TYPE,
but it got OFFSET_TYPE instead.  Which is--in tree.def--described as "a pointer
relative to an object".  Thus I think we should allow OFFSET_TYPE here.  In the
attached testcase I demonstrated that this warning works even for OFFSET_TYPEs.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2015-12-02  Marek Polacek  <pola...@redhat.com>

        PR c++/68653
        * tree.c (nonnull_arg_p): Allow OFFSET_TYPE.

        * g++.dg/warn/nonnull3.C: New test.

diff --git gcc/testsuite/g++.dg/warn/nonnull3.C 
gcc/testsuite/g++.dg/warn/nonnull3.C
index e69de29..d82fa31 100644
--- gcc/testsuite/g++.dg/warn/nonnull3.C
+++ gcc/testsuite/g++.dg/warn/nonnull3.C
@@ -0,0 +1,19 @@
+// PR c++/68653
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wall" }
+
+struct B;
+struct A {
+  template <typename T> __attribute__((nonnull)) bool foo (int T::*);
+  void bar (B *);
+};
+
+template <typename T> bool A::foo (int T::*p)
+{
+  return p;
+}
+void A::bar (B *)
+{
+  foo ((int B::*) nullptr);
+}
+// { dg-warning "nonnull argument" "" {target "*-*-*"} 0 }
diff --git gcc/tree.c gcc/tree.c
index 587bd74..bd5cf73 100644
--- gcc/tree.c
+++ gcc/tree.c
@@ -13848,7 +13848,9 @@ nonnull_arg_p (const_tree arg)
   tree t, attrs, fntype;
   unsigned HOST_WIDE_INT arg_num;
 
-  gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE 
(arg)));
+  gcc_assert (TREE_CODE (arg) == PARM_DECL
+             && (POINTER_TYPE_P (TREE_TYPE (arg))
+                 || TREE_CODE (TREE_TYPE (arg)) == OFFSET_TYPE));
 
   /* The static chain decl is always non null.  */
   if (arg == cfun->static_chain_decl)

        Marek